A second ascent of chemistry's Mt. Everest

Dec 12, 2012
A second ascent of chemistry's Mt. Everest

In science's equivalent of ascending Mt. Everest, researchers are reporting success in one of the most difficult challenges in synthetic chemistry—a field in which scientists reproduce natural and other substances from jars of chemicals in a lab. The feat, reported in the Journal of the American Chemical Society, involved synthesis of a rare substance with promising in vitro anti-cancer effects found naturally in tiny amounts in a Chinese medicinal herb.

Samuel J. Danishefsky and Feng Peng explain that maoecrystal V occurs naturally in a plant growing in China's Yunnan province. Practitioners of have used the herb, called Isodon eriocalyx Hara, for hundreds of years. Scientists isolated maoecrystal V in 1994 and found that it has anti-cancer effects that warrant further examination. Large amounts would be needed to do so. However, the herb contains only small amounts of the material. In one experiment, it took more than 26 pounds of dried leaves to produce 0.00017637 oz. of maoecrystal V. In 2010, the first group of scientists succeeded in making maoecrystal V in a lab. Now, a second group has found a new route to the potential anti-cancer compound.

Danishefsky and Peng describe their approach as providing the basis for a synthesis that may help scientists develop a practical route to the substance for drug development and other research. It yielded a mixture of the two enantiomeric forms of maoecrystal V. They are pursuing several improvements, including a way to control the reactions to yield only a single of the substance.

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More information: "Total Synthesis of (±)-Maoecrystal V" J. Am. Chem. Soc., 2012, 134 (45), pp 18860–18867. DOI: 10.1021/ja309905j

Abstract
The total synthesis of racemic maoecrystal V has been accomplished. Key steps include an intramolecular Diels–Alder cyclization to rapidly construct the core system from simple starting materials and the creation of the A–C ring trans-fusion through intramolecular delivery of a hydrogen to the hindered β-face of the ring system.

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Lurker2358
not rated yet Dec 12, 2012
However, the herb contains only small amounts of the material. In one experiment, it took more than 26 pounds of dried leaves to produce 0.00017637 oz. of maoecrystal V.


Yet that insanely small concentration was effective enough that traditional herbalists discovered it actually worked. That suggests that the pure compound should be incredibly powerful indeed.
Tausch
1 / 5 (1) Dec 20, 2012
Wonder what traditional herbalists found this herb good for in a search for a treatment of indications their patients exhibited.

What were the traditional herbalists trying to treat and/or cure in their patients?

Modern herbalists - chemists - test for the cytotoxicity of all compounds isolated against colon carcinoma (HT-29), hepatic carcinoma (BEL-7402), and ovarian (SK-OV-3) human cell lines using a method
described in the literature,43 with adriamycin as the positive control.

http://210.72.88....0048.pdf
Tausch
1 / 5 (1) Dec 20, 2012
Congratulations to the researchers and the successful research.
Berg Heil!